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Sep 28, 2012, 08:42 PM
Registered User
Here is another idea I had while doing some more research and investigation on the full-scale.

The Full-scale had its turbine located fairly far forward. The EDF's on the plans are located about 35-45% of the chord, and the inlets are about 1-2" in diameter large than they need to be (larger than scale). So if we reduce the inlet size down to 90mm diameter and move the EDF units as far forward as we can (about 2" aft of the leading edge) This would allow a good bit of the duct extensions to remain inside of the airplane.

Do you guys think this would allow the air enough time to straighten itself out and still fly well, or would the duct extensions still need to extend aft of the wing TE?

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Sep 28, 2012, 09:45 PM
Pro Hoarder
turbonut's Avatar
HI Thomas, I have been looking at the same thing on my Ho.also I noted that when you look down the intake from the front the tail cuts into the airstream.So I made my cut out aft of the exit a bit longer than orig for the kit. the exit is also a bit more inset than scale.I think to make the mold not go negitive but it all just needs more testing.I plan to use stater vanes in the tail pipe to correct spiral flow and mabe a control vane at the exit that will direct eflux Like I have seen on the smaller Ho.
Sep 28, 2012, 09:47 PM
Registered User
Yea I was seeing the same thing. I'm pretty sure I am going to reduce the inlet area to "scale" since with the 90mm EDF units we can get plenty of power from them now to fly an airplane that is 15ish pounds. I Really need to get my hands on a set of Bentley drawings for this thing! I have been trying for months to get ahold of him to order a set with no luck.
Sep 29, 2012, 10:53 PM
Registered User
Well after a day or 2 of building a plug, molding and then trimming and fitting a cooling baffle on my 35% Extra 260, And doing some maintenance / fine tuning on other airplanes in the fleet, I have finally gotten back onto the HO-229.

I started working on this thing about 3-4pm today. It is amazing how much faster the second wing progress' after you have learned it all on the first wing. So, the second wing panel is nearly ready for sheeting. All that is left, is to do the elevon hinging holes, profile the leading edge of the ribs and the sub leading edge, install the drag rudders and the servo mounting plate for the drag/elevon servo.

First up, install the hinge hard points:

Then attach the sheeting jigs to the table and then the wing to the jig:

Then Main spars, shear webbing, servo conduits, and more hinge hard points:

Then align and glue in the wing tube sockets. The white paste you see is epoxy and cotton flock mixture. This makes a very strong and light glue, plus you can make it as thick or runny as you need it:

And then the wing tube anti-rotation/attachment bolt blocks and hardpoint (1/2" hardwood dowel inset into the hard balsa blocks) are epoxied to the wing tubes:

And, I had a wild hair and thought, what the heck.. thats the inspiration for this photo!

So, a couple of hints for the guys building these things:

1. Do NOT install the lower forward wing spar when you are initially framing up the wing. If you do, you will have to remove it later in order to set the correct washout in the sheeting jigs.

2. When you install the Flap sub-spars, install them per the plans. THEN install another pair that is butted up against the TE side of the first set. Don't glue the two sub-spars together though. Actually, better yet, would be to install the upper one about 1/4-3/8" aft of the top sub spar, and the bottom ones about 1/8" aft. Reason for this, is it gives you a more robust edge, so when you go to separate the flaps from the wings, if gives you a known edge to cut to AND gives the flaps some more structure.

3. Use the dubro "snap on" style ball-links for the drag rudders instead of the Z bends like what I show in this build. The ball-links will give you a straighter linkage, and will be easier to remove/install if you ever have to remove/replace the drag rudder servo.

4. I'll add more later, but the above three are pretty much the major ones.
Sep 30, 2012, 10:44 PM
Registered User
Well.. the other wing is getting closer to being done. All that is left, is installing the drag rudders and sheeting the bottom of this wing panel. Then, this wing panel will be at the same stage as the other. I suspect that I will have both of these wing panels done by the end of the month and ready for glassing. It'd be sooner, but i have to go to Puerto Rico for a week for work.

Oct 04, 2012, 07:15 AM
Scale Designer/Builder
Well well, Horten addicts just never get enough I see :-) John, Heiner - glad to see you guys are still at it. This project is coming along nicely. I'm glad to see more and more problems worked out. There's clearly been a lot of progress in understanding and working around the exhaust turbulence problem. Best of luck with your project. I'm looking forward to seeing your molding work on the center section. That was one of my favorite parts. Do be cautious with the exhaust extensions, but I'm glad to see you're motivated to eliminate them.

Last edited by ghethco; Oct 04, 2012 at 07:16 AM. Reason: forgot URL
Oct 04, 2012, 11:10 AM
Registered User
Nice work, the wings and drag rudders are coming along nicely. I decided not to do the drag rudders- too much work! lol . She turns fine with the Frise ailerons and about 10% aileron differential, which you can only program in Elevon mode w/ newer Futaba and possibly JR computer radios, the other brands do not have the differential feature when in elevon mode .
BTW, drag from the bottom edges of the Frise ailerons has not been an issue during elevator inputs. Mine will do loops, for example, without difficulty.
As Gary, Hiener, and myself have said, not to be redundant, but *use caution with any shortening/altering of the exhaust extensions*.


PS: Hi Gary, how's it going Bud!? Havn't started the little one yet, still finishing up my foam experiment, she is looking good so far.
Last edited by Horten Freak; Oct 13, 2012 at 05:57 AM. Reason: Additional info.
Oct 04, 2012, 11:12 AM
Registered User
Good to hear on the elevator input! I should have both wing panels completed to the same stage by the weekend, and possibly ready for glassing by the end of the weekend.

Last edited by invertmast; Oct 04, 2012 at 12:24 PM.
Oct 04, 2012, 12:23 PM
was geht , müssen unten kommen
Keenan smith's Avatar
yah may want some expo on the drag rudders channels... so you dont spin it...
Oct 07, 2012, 12:00 AM
Registered User
Alright.. left and right wings are at the same stage. All that is left to do to them is:

1. Install and shape Leading edge
2. Install and shape wingtip blocks
3. Cut free, hinge and install elevon LE
4. Cut free, hinge and install Flap LE and wing TE
5. Trim wing trailing edge to final shape
6. Cut elevon/drag rudder and flap access hatch's out of wing and install mounting rails.
7. Glass and paint
Oct 07, 2012, 10:53 PM
Registered User
The left wing is now completed to the same stage as the Right wing panel:

Then my buddy called and said he busted his last bandsaw blade and didn't have any extra's and asked if he could come over to help cut out the rest of the parts for the center section... so of course I couldn't say no! So, here is the center section and all of its pieces fit together... There is NO glue in this assembly, it is just all tabbed and set together.

Once we saw that, we had to do a mock up photo.. so i pulled the wing tubes out of the left wing panel (I made sure to make index marks between the wing root rib and the tube so it is easier to re-install the tubes later), then we mocked up the left wing panel the the center section:

And of course, once we did this, we HAD to do the same with the other wing (this wing also had its wingtip and leading edge installed and rough shaped as well)

*HOLY CRAP, this thing is HUGE... again, that is a 4'x8' table!

A shot from the front... it definitely has that Horton look!

And another with one of the Changesun 90mm 12blade EDF units mocked up into place. We quickly spoke about possibly doing twin 120mm setups, but after pricing them, and realizing it would add about 3-4lbs of weight over the dual 6s 90mm EDF setups, it was decided the weight and increased cost (nearly 3 times as much!) was not worth it. Afterall, we have the possibility of doing 8,10 or 12s lipo with the 90mm setup as well.

Oct 08, 2012, 09:05 AM
was geht , müssen unten kommen
Keenan smith's Avatar

Oct 08, 2012, 09:41 AM
Pro Hoarder
turbonut's Avatar


Hey Gary, nice to know you are watchin...

Lookin good guys are cranking this out fast...I need to get back to mine..

Originally Posted by ghethco
Well well, Horten addicts just never get enough I see :-) John, Heiner - glad to see you guys are still at it. This project is coming along nicely. I'm glad to see more and more problems worked out. There's clearly been a lot of progress in understanding and working around the exhaust turbulence problem. Best of luck with your project. I'm looking forward to seeing your molding work on the center section. That was one of my favorite parts. Do be cautious with the exhaust extensions, but I'm glad to see you're motivated to eliminate them.

Oct 08, 2012, 09:58 AM
Registered User
Thanks guys. So far, we are in track to have the center section plug completed by the end of november. I have all of the glass needed for the mold, i just need to order some more epoxy. I believe we should have the molds completed by the end of december, and the first full airframe ready for final installation of all the systems by mid feb to march! We will then fly the pants off this thing to see what kind of mods or changes need to be made while the second one is getting finished.

We did some measuring, and we are planning on pushing the fans forward to where they are mounted 2 inches aft of the leading edge of the wing. That will make our exhaust ducts 24.5" long.
I also have an idea on doing some tests with the center section strapped to the trunk of a car
Oct 09, 2012, 03:10 AM
Registered User

Now it looks like a Horten!! I well remember when I reached this stage with mine and was able to fit the wings on the centre section. Great feeling.

I am amazed how quickly you are building. Yes some data from a car roof and tufts on the centre section make a lot of sense. This will not be a rocket ship and you should get some useful data.

I am also wondering about C of G position and how the instability is affected by a change. On mine the C of G moves back significantly as the retracts are pulled up. Not sure what size your wheels will be and how the nose leg will be pulled up. I used Heiner's method with an additional strut. This pulls up a frame that the wheel retracts into. I hope the photos will help. This arrangement has been trouble free since installation. I made the pull up ram as I couldn't find one of the length I needed, about 11 inches.


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